Communication device and power control method thereof

ABSTRACT

A communication device and a power control method thereof are provided. The power control method, performed by a communication device, includes: determining a power range of a transmit power of an uplink signal; determining a gain switch range based on the power range; when the transmit power of the uplink signal is within the gain switch range, determining a first gain mode for amplifying the uplink signal; and when the transmit power of the uplink signal is out of the gain switch range, determining a second gain mode for amplifying the uplink signal.

CROSS REFERENCE TO RELATED APPLICATIONS

This Application is a reissue of U.S. Pat. No. 9,042,936, issued on May26, 2015, which claims priority of Taiwan Patent Taiwanese ApplicationNo. 101142565, filed on Nov. 15, 2012, and the entirety of which is areincorporated by reference herein.

BACKGROUND

1. Field

The present disclosure relates to a power control mechanism, and inparticular, a communication device and a power control method thereof.

2. Description of the Related Art

In recent years, users have changed their way of using mobilecommunication devices such as a smart phone or a tablet, by blogging andsharing their daily life experiences, increasing communication for workand business, and using the mobile communication devices for educationand entertainment. Accordingly, network operators have increased thebandwidth for mobile networks in order to meet an expanding range ofuser applications.

A power amplifier (PA) plays an important role in a radio frequency (RF)transmitter circuit of a mobile communication device, serving to amplifya signal before driving the signal on the communication channel. The PAis typically placed next to the antenna, and consumes the most power inthe transmitter circuit. As the requirement for radio bandwidthincreases, the power consumption at the transmitter circuit becomes acrucial issue for designers. In order to increase a Power AddedEfficiency (PAE) of the PA, the circuit design of the PA deploys severalgain modes. The adjacent gain modes overlap with each other. With theemployment of PA switch points (PASP) for the gain modes, the poweramplifier can provide continuous and stable linear transmit power. Sincethe PA employs several gain modes, circuit designers are required toconsider the overlapping coverage of the gain modes for the transmittercircuit to determine a set of PASPs. The determining of the set ofPASPs, negatively impacts circuit performance and battery life of amobile communication device.

BRIEF SUMMARY OF THE DISCLOSURE

A detailed description is given in the following embodiments withreference to the accompanying drawings.

An embodiment of a power control method is disclosed, performed by acommunication device, comprising: determining a power range of atransmit power of an uplink signal; determining a gain switch rangebased on the power range; when the transmit power of the uplink signalis within the gain switch range, determining a first gain mode foramplifying the uplink signal; and when the transmit power of the uplinksignal is out of the gain switch range, determining a second gain modefor amplifying the uplink signal.

Another embodiment of a communication device is provided, comprising acontroller and a power amplifier. The controller is configured todetermine a power range of a transmit power of an uplink signal, anddetermine a gain switch range based on the power range, and when thetransmit power of the uplink signal is within the gain switch range,determine a first gain mode and when the transmit power of the uplinksignal is out of the gain switch range, determine a second gain mode.The power amplifier, coupled to the controller, is configured to amplifythe uplink signal with the first or the second gain mode.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure can be more fully understood by reading thesubsequent detailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1 illustrates a switch mechanism switching a gain mode for a PowerAmplifier PA of a communication device according to an embodiment of thedisclosure.

FIG. 2 is a block diagram of a communication device 2 according to anembodiment of the disclosure.

FIGS. 3A and 3B are a flowchart of a switch method 3 switching gainmodes for a power amplifier.

FIG. 4 illustrates a distribution of the PA parameters of the poweramplifier according to an embodiment of the disclosure.

FIG. 5 is a flowchart of another switch method 5 switching gain modesfor a power amplifier.

DETAILED DESCRIPTION OF THE DISCLOSURE

The following description is of the best-contemplated mode of carryingout the disclosure. This description is made for the purpose ofillustrating the general principles of the disclosure and should not betaken in a limiting sense. The scope of the disclosure is bestdetermined by reference to the appended claims.

FIG. 1 illustrates a switch mechanism switching a gain mode for a PowerAmplifier PA of a communication device according to an embodiment of thedisclosure, where the horizontal axis represents a power of the PA, andthe vertical axis represents a power of the communication device. Theembodiment shows two gain modes for the power amplifier PA, including alow gain mode 10 and a high gain mode 12. The power amplifier PA isconfigured to switch between the low gain mode 10 and the high gain mode12 based on one of three possible gain switch ranges S1, S2, and S3, andamplify the power for an uplink signal according to the switched lowgain mode 10 or the high gain mode 12, thereby driving the amplifieduplink signal on an appropriate communication channel. The communicationdevice can select one from the three possible gain switch ranges S1, S2and S3 based on a characteristic of the required transmit power of theuplink signal, thereby controlling the gain mode adopted by the poweramplifier PA. The communication device may be a smart phone, a tablet, alaptop or another electronic device with a wireless communicationcapability.

After the design architecture of a radio frequency (RF) transmittercircuit is decided, the possible gain switch ranges for the RFtransmitter circuit can also be determined, accordingly. The gain switchranges for the power amplifier PA is an adaptable range between theswitching points of the gain modes, or within the range of power P1through P6 in FIG. 1. Further, the gain switch ranges for the poweramplifier PA may include the three possible gain switch ranges S1, S2and S3.

In the gain switch range S1, when the power amplifier PA is in the lowgain mode 10 and the required PA power exceeds the power P2, the poweramplifier PA is configured to switch to the high power mode 12 toamplify the power of the uplink signal. Conversely, when the poweramplifier PA is in the high gain mode 12 and the required PA power islower than the power P1, the power amplifier PA is configured to switchto the high power mode 10 to reduce the power amplification of theuplink signal. In comparison to the other gain switch ranges S2 and S3,since the switching point of the gain modes falls onto the high gainmode 12 in advance, the power amplifier PA allows for increased linearamplification headroom while increasing the power consumption. The gainswitch range S1 is preferred for the wireless communication systemswhich require increased modulation such as 16 QAM or 64 QAM, andincreased transmit speed or bandwidth such as the Wideband Code DivisionMultiple Access (W-CDMA) technology, the Carrier Aggregation (CA) of theLong Term Evolution-Advanced (LTE-A), and the multiplex of thesub-carriers such as an OFDM or multi-layer modulator. The gain switchrange S1 can be implemented for the telecommunication technologies suchas the versions Rel-5, Rel-6 and Rel-7 (W-CDMA), the versions Rel-8 andRel-9 (Long Term Evolution, LTE), and the versions Rel-10, Rel-11, andlater versions (LTE-A). Similar communication systems include high-speedtransmission transmitters for the IEEE 802.11n/ac/ad systems.

In the gain switch range S2, when the power amplifier PA is in the lowgain mode 10 and the required PA power exceeds the power P6, the poweramplifier PA is configured to switch to the high power mode 12 toamplify the power of the uplink signal. Conversely, when the poweramplifier PA is in the high gain mode 12 and the required PA power islower than the power P5, the power amplifier PA is configured to switchto the high power mode 10 to reduce the power amplification of theuplink signal. In contrast to the gain switch range S1, the gain switchrange S2 has an increased probability to stay in the low gain mode 10.As a consequence, the power amplifier PA requires less powerconsumption. In particularly, the gain switch range S2 may cause signaldistortion for certain RF signal transmission modes. For example,certain combinations of modulations in the physical layer or first layerand radio resource scheduling can result in an increased peak-to-averageratio (PAPR). The gain switch range S2 is preferred for wirelesscommunication systems with reduced transmission speeds and modulationtechnologies, e.g., BPSK or QPSK modulation technologies and multiplextechnologies for small numbers of channels in the physical layers.

The gain switch range S3 prevents the power amplifier PA from consumingexcessive power as in the gain switch range S1, and insufficient powerheadroom as in the gain switch range S2, providing an alternative for aflexible and compromised solution for the power amplifier PA.

The embodiments can prolong the battery life of the communicationdevice, providing a solution for dynamically adapting the gain switchrange for the power amplifier PA, thus, increasing the battery life ofthe communication device.

FIG. 2 is a block diagram of a communication device 2 according to anembodiment of the disclosure, including a radio frequency (RF) circuit20, a control circuit 22, a memory 24 and a bus 26 (one or moretransmission interfaces). The RF circuit 20, the control circuit 22 andthe memory 24 communicate and exchange data via the bus 26. Thecommunication device 2 can be implemented to realize the multi-switchrange mechanism depicted in FIG. 1. In particularly, the communicationdevice 2 is configured to estimate a required power range for the poweramplifier PA, and select one of a plurality of switch ranges based onthe estimated power range for use in the power amplifier PA.

The RF circuit 20 is configured to transmit an uplink signal to andreceive a downlink signal from the air interface. The control circuit 22is configured to perform various baseband signal processing andcommunication protocol processing procedures in the communication modemor communication CPU module. The baseband signal processing performed bythe control circuit 22 includes determining the radio resource assignedto the communication device 2 by the network system and the signalquality of the environment. The memory 24 is configured to store programcodes and data such as the operation system programs and userapplication programs, and collecting information on the times, locationsor software used by the wireless module on the communication device 2,so that the control circuit 22 can analyze the PA gain switch ranges orthe transmit power associated messages to adaptively adjust parametersfor the power amplifier PA. The control circuit 22 and memory 24 areconfigured to provide external information functionalities and internalinformation functionalities for adjusting the PA gain switch rangesadaptively, so that the PA gain switch range of a power amplifier PA 200can be optimized for the battery life based on user behavior orconditions of the wireless environment.

The RF circuit 20 includes the power amplifier PA 200 and an RFfront-end circuit 202. The RF circuit 20 may further include a matchcircuit, various filters and wiring layouts (not shown). After thehardware architecture is determined, the communication device 2 candetermine a set of PA gain switch ranges for the FR circuit 20 via theRF calibration procedure during the device startup or the factory test,thereby acquiring stable efficiency for the RF circuit 20. The poweramplifier PA 200 includes two or more gain modes such as high,intermediate and low gain modes. Each gain mode has two or more gainswitch ranges controlled and selected by the control circuit 22. Forexample, the low gain mode has two gain switch ranges, one providing anincreased transmit power headroom for the power amplifier, and the otherpreventing a power amplifier from consuming excessive power. In someembodiments, the power amplifier PA 200 can receive a gain controlsignal from the control circuit 22 to select one of a plurality of gainmodes for amplifying the power of the uplink signal and driving theamplified uplink signal to a receiver, base station, or a networksystem.

The control circuit 22 includes a controller 220, a communicationprotocol module 222 and external information module 224, configured toprocess all data and information associated with the environmentexternal to the communication device 2. The control circuit 22 isconfigured to compute the transmit power of the uplink signal accordingto the processed data and information, and determine the PA gain switchrange based on the computed transmit power for the uplink signal. Theinformation or data associated with external environment include thenetwork resource assignment and the wireless channel environment. Thenetwork system can assign limited radio resources including RadioResource Management (RRM), Transmit Power Control (TPC), and Quality ofService (QoS) to the wireless communication devices in the coverage. Thecontrol circuit 22 can compute a transmit power for the uplink signalbased on the assigned radio resources. For example, the network systemcan assign a plurality of carriers, certain transmit powers, and areal-time QoS to the communication device 2. The communication protocolmodule 222 is configured to interpret the system information sent fromthe network system to acquire the information on the assigned carriers,the transmit power and the QoS. Then the controller 220 is configured tocompute the transmit power of the uplink signal and the distribution ofthe transmit powers of the uplink signals based on the acquiredinformation on the assigned carriers, the transmit power and the QoS. Insome embodiments, the communication protocol module 222 can communicatewith the network system with a shared communication protocol, thereby,adjusting the PA gain switch mode to increase the battery life.Moreover, since the network system adopts various types of basestations, including macrocells, microcells, picocells, femtocells orother types of cells and various types of service versions, the signalinterferences in the radio channel can vary with user environment.Accordingly, the external information module 224 in the control circuit22 is configured to compute the PA gain switch range and the radiochannel estimation to compute a Signal to Interference and Noise Ratio(SINR), so that the controller 220 can determine the transmit power ofthe uplink signal and the distribution of the transmit powers of theuplink signals based on the computed SINR. Finally, the controller 220is configured to determine the gain switch range of the power amplifierPA 200 according to the determined distribution of the transmit powersof the uplink signals, and determine one PA gain mode according to thedetermined gain switch range and the transmit power of the uplinksignal, and pass the determined PA gain mode to the power amplifier PA200 by a gain control signal, thereby amplifying the power for theuplink signal. For example, when the transmit power of the uplink signalexceeds an upper switch point of the gain switch range, the controller220 is configured to switch the power amplifier PA 200 to an increasedlevel of the gain modes. Whereas, when the transmit power of the uplinksignal is less than a lower switch point of the gain switch range, thecontroller 220 is configured to switch the power amplifier PA 200 to adecreased level of the gain modes. When the transmit power of the uplinksignal is within the upper switch point and the lower switch point ofthe gain switch range, the controller 220 is configured to remain in acurrent gain mode. The communication protocol module 222 and theexternal information module 224 may be a digital circuit (e.g., digitalsignal processor, DSP) or a memory with an associated driving program.The distribution of the transmit power of the uplink signal and thecorresponding gain switch range can be recorded in a lookup table in amemory device in the control circuit 22 or in other locations.

The memory 24 includes a user application program 240 and internalinformation program 242, configured to process data associated with theinternal data of the communication device 2. A processor or controller(not shown) can access the program codes in the user application program240 or the internal information program 242 and execute the programcodes, accordingly. In some embodiments, the controller 220 in thecontrol circuit 22 can access the user application program 240 or theinternal information program 242, collect the information on the times,locations and associated software used on the communication device 2,analyze the PA gain switch ranges or transmit power associated messagesand accordingly adapt the parameters for the power amplifier PA 200. Forexample, the user can specify an upload speed, a bandwidth limit or adata stream limit for a certain time, location, network service orsoftware, then the controller 220 can estimate the transmit power of theuplink signal and the distribution of the transmit powers of the uplinksignals according to the specified upload speed, the bandwidth limit orthe data stream limit, thereby determining a gain switch range for thepower amplifier PA 200 based on the estimated the transmit power of theuplink signal and the distribution of the transmit powers of the uplinksignals. The controller 220 can access the internal information program242 from the memory 24 to analyze the information on the times,locations, associated services and software, to derive a statisticalmeasure, thereby acquiring the corresponding gain switch range. When thecommunication device 2 requests for a network service later, theinternal information program 242 can determine a corresponding gainswitch range for use in the controller 220 based on the analyzedinformation. The controller 220 is configured to determine a PA gainmode based on the corresponding gain switch range and the transmit powerof the uplink signal, and send the gain determined by the PA gain modevia the gain control signal to the power amplifier PA 200, amplifyingthe power of the uplink signal. The distribution of the transmit powerof the uplink signal and the corresponding gain switch range can berecorded in a lookup table in the memory 24 or in memory at otherlocations.

FIGS. 3A and 3B are a flowchart of a switch method 3 switching gainmodes for a power amplifier, incorporating the communication device 2 inFIG. 2.

After the communication device 2 is initialized, it can determine a gainswitch range according to the internal information functionalitiesassociated with user behavior or demands and the external informationfunctionalities. Regarding the internal information functionalities, thecontroller 220 is configured to check whether an option for the internalinformation functionalities has been activated (S300). If the option hasnot been activated, the controller 220 is configured to regularly orcontinuously determine the status of the option for the internalinformation functionalities (S300).

If the option has been activated, the controller 220 is configured toproduce the uplink signal based on the internal information, anddetermine a PA parameter representing the distribution of the transmitpowers of the uplink signals (S302). The controller 220 can execute theuser application program 240 and the internal information program 242 togenerate the internal information. For example, the user applicationprogram 240 may be used to retrieve the internal information input bythe user, such as the upload speed, the bandwidth limit or the datastream limit, and the controller 220 is configured to concurrentlygenerate one or more digital output data according tot the inputinternal information, and sum all of the digital output data together tocompute the first PA parameter. The first PA parameter may be a sum ofall powers of the digital output data, or the value of the sum of thepowers converted in dBm or in a quantization unit. After a period ofdata collection expired, the controller 220 can establish a distributionof the first PA parameters representing the distribution of the transmitpowers of the uplink signals. FIG. 4 illustrates a distribution of thePA parameters of the power amplifier according to an embodiment of thedisclosure, including two uplink signals designated by load 1 and load 2in dBm. As illustrated, the distribution of the PA parameter directlycorresponds to the distribution of the required transmit powers of theuplink signals. Each uplink signal includes a parameter range PA−, anaverage, a parameter range PA+ and a front-end loss potion (FE loss).The parameter range PA− covers a range from the lower limit of the PAparameters to the average of the PA parameters, and the parameter rangePA+ covers a range from the average of the PA parameters to the upperlimit of the PA parameters. The FE loss is the power consumption in theRF circuit 20 including the RF front-end circuit 202.

After producing a distribution of the PA parameters as illustrated inFIG. 4, the controller 220 is configured to determine a first gainswitch range based on the distribution of the PA parameters (S304). Forexample, when the first PA parameters are the distribution of the load 1in FIG. 4, since the distribution of the PA parameters is across a smallrange of the powers PA2-PA3, the controller 220 can select the gainswitch range S2 in FIG. 1 as the first gain switch range, so that thepower amplifier PA 200 has an increased time operating in the low gainmode, in comparison to other gain switch ranges. When the first PAparameters are the distribution of the load 2, as illustrated in FIG. 4,since the distribution of the PA parameters is across a large range ofthe powers PA1-PA3, the controller 220 can select the gain switch rangeS1 in FIG. 1 as the first gain switch range, so that the power amplifierPA 200 has an increased time operating in the high gain mode, incomparison to other gain switch ranges. In other embodiments, thecontroller 220 is configured to determine the first gain switch rangeaccording to the distribution of the PA+ parameters. With reduceddistribution of the PA+ parameters, the controller 220 is configured todetermine the first gain switch range that has an increased timeoperating the power amplifier PA 200 under a lower gain mode.Conversely, with increased distribution of the PA+ parameters, thecontroller 220 is configured to determine the first gain switch rangethat has an increased time operating the power amplifier PA 200 under ahigher gain mode.

Referring again to FIG. 3, the controller 220 can next determine whetherthe determined first gain switch range is different from the previousfirst gain switch range (S305). If the two first gain switch ranges areidentical, the switch method 3 is configured to return to performingStep S302 for re-computing the PA parameters for the uplink signals. Ifthe two first gain switch ranges are different, the switch method 3 isconfigured to evaluate whether the newly determined first gain switchrange would degrade the RF efficiency of the power amplifier PA 200(S306). The controller 220 is configured to compute an Adjacent ChannelLeakage Power Rate (ACLR), Error Vector Magnitude (EVM), transmitpowers, SNR or QoS parameters for the amplified uplink signals, therebyevaluating the present RF efficiency of the power amplifier PA 200. Whenthe determined first gain switch range causes unstable networkconnection or unsatisfactory QoS for RF efficiency, the controller 220is configured to retain the previous first gain switch range and theswitch method 3 is configured to go back to Step S302 for re-computingthe PA parameters. When the determined first gain switch range renderssatisfactory RF efficiency, the switch method 3 is configured to performStep S316. Step S306 is an optional step. In some embodiments, theswitch method 3 can perform Step 316 without performing Step S306.

Regarding the external information functionalities, the controller 220is configured to check whether an option for the external informationfunctionalities has been activated (S300). If the option has not beenactivated, the controller 220 is configured to regularly or continuouslydetermine the status of the option for the external informationfunctionalities (S308).

If the option has been activated, the controller 220 is configured toproduce the uplink signal based on the external information, anddetermine a PA parameter representing the distribution of the transmitpowers of the uplink signals (S310). The external information may begenerated by the controller 220, the communication protocol module 222or the external information module 224. For example, the communicationprotocol module 222 may be used to retrieve the system information sentfrom the network system to acquire information on the number ofcarriers, the assigned transmit power and the quality of service. Theexternal information module 224 is configured to compute the SINRparameter in the radio channel according to the received downlinksignal. Next, the controller 220 can estimate one or more digital outputdata based on the external information such as the number of carriers,the assigned transmit power, the quality of service, the SINR or otherexternal information, and sum all of the digital output data together tocompute the second PA parameter. The second PA parameter may be a sum ofall powers of the digital output data, or the value of the sum of thepowers converted in dBm or in a quantization unit. After a period ofdata collection, the controller 220 can acquire a distribution of thesecond PA parameters representing the distribution of the transmitpowers of the uplink signals. FIG. 4 illustrates a distribution of thePA parameters of the power amplifier according to an embodiment of thedisclosure, including two uplink signals designated by load 1 and load 2in dBm. As illustrated, the distribution of the PA parameter directlycorresponds to the distribution of the required transmit powers of theuplink signals. Each uplink signal includes a parameter range PA−, anaverage, a parameter range PA+ and a front-end loss potion (FE loss).The parameter range PA− covers a range from the lower limit of the PAparameters to the average of the PA parameters, and the parameter rangeis PA+ covers a range from the average of the PA parameters to the upperlimit of the PA parameters. The FE loss is the power consumption in theRF circuit 20 including the RF front-end circuit 202.

After producing a distribution of the PA parameters as illustrated inFIG. 4, the controller 220 is configured to determine a second gainswitch range based on the distribution of the PA parameters (S312). Forexample, when the first PA parameters are the distribution of the load 1as illustrated in FIG. 4, since the distribution of the PA parameters isacross a small range of the powers PA2-PA3, the controller 220 canselect the gain switch range S2 in FIG. 1 as the second gain switchrange, so that the power amplifier PA 200 has an increased timeoperating in the low gain mode, in comparison to other gain switchranges. When the second PA parameters are the distribution of the load 2as illustrated in FIG. 4, since the distribution of the PA parameters isacross a large range of the powers PA1 -PA3, the controller 220 canselect the gain switch range S1 in FIG. 1 as the second gain switchrange, so that the power amplifier PA 200 has an increased timeoperating in the high gain mode, in comparison to other gain switchranges. In other embodiments, the controller 220 is configured todetermine the second gain switch range according to the distribution ofthe PA+ parameters. With less distribution of the PA+ parameters, thecontroller 220 is configured to determine the second gain switch rangethat has an increased time operating the power amplifier PA 200 under alower gain mode. Conversely, with increased distribution of the PA+parameters, the controller 220 is configured to determine the secondgain switch range that has an increased time operating the poweramplifier PA 200 under a higher gain mode.

Next, the controller 220 can determine whether the determined secondgain switch range is different from the previous second gain switchrange (S313). If the two second gain switch ranges are identical, theswitch method 3 is configured to return to performing Step S310 forre-computing the PA parameters for the uplink signals. If the two secondgain switch ranges are different, the switch method 3 is configured toevaluate whether the newly determined second gain switch range wouldresult in degradation of the RF efficiency for the power amplifier PA200 (S314). Step S314 is an optional step. In some embodiments, theswitch method 3 can perform Step 316 directly without performing StepS314. The controller 220 is configured to compute an ACLR, EVM, transmitpowers, SNR or QoS parameters for the amplified uplink signals, therebyevaluating the present RF efficiency of the power amplifier PA 200. Whenthe determined second gain switch range causes unstable networkconnection or unsatisfactory QoS variation in the RF efficiency, thecontroller 220 is configured to retain the previous second gain switchrange and the switch method 3 is configured to again perform Step S310for re-computing the PA parameters. When the determined second gainswitch range renders a satisfactory RF efficiency, the switch method 3is configured to perform Step S316.

Since the switch method 3 deploys the internal informationfunctionalities or the external information functionalities to determinethe gain switch range, there could be 4 possible conditions, i.e., theinternal information functionalities is activated while the externalinformation functionalities is inactivated, the internal informationfunctionalities is inactivated while the external informationfunctionalities is activated, both the internal and external informationfunctionalities are activated, or both the internal and externalinformation functionalities are inactivated. In the condition where boththe internal and external information functionalities are activated aconfliction may arise between the gain switch ranges determined by theinternal and external information. Thus, the switch method 3 performsSteps S316 through S320 to determine the gain switch range to be adoptedby the power amplifier PA 200. In Step S316, the controller 220 isconfigured to compare the first and second gain switch ranges. When thetwo gain switch ranges are the same, the controller 220 is configured toemploy the same gain switch range and the required power of the uplinksignal to determine a gain mode for the power amplifier PA 200 (S324),and then the switch method 3 is completed and exited (S326). When thefirst and second gain switch ranges are different, the controller 220 isconfigured to select one of the first and second gain switch ranges asthe gain switch range to be adopted by the power amplifier PA 200(S318). In some embodiments, the controller 220 is configured to assigna first priority and a second priority to the internal informationfunctionalities and the external information functionalitiesrespectively, and the first and second priorities are different. Thecontroller 220 is configured to determine which one of the first andsecond gain switch ranges is to be used as the adopted gain switchrange. For example, the controller 220 can assign a higher priority tothe internal information functionalities than to the externalinformation functionalities. When the first gain switch range isdifferent from the second one, the controller 220 will select the firstgain switch range which corresponds to the internal informationfunctionalities as the gain switch range to be used. In otherembodiments, the controller 220 can determine a gain switch rangecorresponding to a smaller or reduced distribution of the PA parameters(the reduced power range of the transmit power) in the two distributionsof the PA parameters (the first and second power ranges) as the gainswitch range to be adopted, increasing the battery life of thecommunication device 2. In yet other embodiments, the controller 220 candetermine a gain switch range corresponding to a larger or increaseddistribution of the PA parameters (the increased power range of thetransmit power) in the two distributions of the PA parameters (the firstand second power ranges) as the gain switch range to be adopted,increasing the signal quality of the uplink transmission for thecommunication device 2. Then the controller 220 can adopt the determinedgain switch range and the required power of the uplink signal todetermine the gain mode for the power amplifier PA 200 (S324). At thispoint the switch method 3 is completed and exited (S326).

The switch method 3 utilizes a plurality of gain switch ranges betweentwo gain modes, allowing the communication device 2 to select anappropriate switch range for use by the power amplifier, rendering boththe battery life and the signal quality of the uplink transmissionimproved.

FIG. 5 is a flowchart of another switch method 5 switching gain modesfor a power amplifier, incorporating the communication device 2 in FIG.2.

After the communication device 2 is initialized, it can generate theuplink signal according to the transmission information (S500). Thetransmission information includes the internal information or theexternal information. The internal information may be the upload speed,the bandwidth limit, the data stream limit and other internalinformation configured by the communication device 2. The internalinformation may be the information on the number of carriers, theassigned transmit power, the quality of service, and other informationregarding the external environment of the communication device 2. Next,after a period of data analysis for transmit powers of the uplinksignals, the controller 220 can determine the power range of therequired powers for the uplink signals (S502), and determine the gainswitch range based on the power range (S504). Referring now to FIG. 4and FIG. 1, when the power range of the required power is the load 1 asillustrated in FIG. 4, the controller 220 can select the gain switchrange S2 in FIG. 1 as the gain switch range. The communication device 2can determine whether the transmit power of the uplink signal is withinthe gain switch range, i.e., whether the transmit power of the uplinksignal is between the upper limit and lower limit of the gain switchrange. Taking FIG. 1 as an example, when the gain switch range S2 isselected, the communication device 2 can determine whether the transmitpower of the uplink signal is between the powers P5 and P6. If so, thecommunication device 2 can amplify the uplink signal with the first gainmode (S508). In the example of selecting the gain switch range S2 asillustrated in FIG. 1, when the transmit power of the uplink signal isout of the gain switch range, i.e., the transmit power of the uplinksignal is less than the power P5 or exceeds the power P6, thecommunication device 2 can amplify the uplink signal with the secondgain mode (S510). The first gain mode is different from the second gainmode, wherein the first gain mode is a default value loaded by thecommunication device 2 during circuit initialization or the last valueadopted by the communication device 2. When the transmit power of theuplink signal is less than the power P5, the second gain mode is lowerthan the first gain mode. Whereas when the transmit power of the uplinksignal exceeds the power P6, the second gain mode is higher than thefirst gain mode.

The switch method 5 utilizes a plurality of gain switch ranges betweentwo gain modes, allowing the communication device 2 to select anappropriate switch range for use by the power amplifier, rendering boththe battery life and the signal quality of the uplink transmissionimproved.

As used herein, the term “determining” encompasses calculating,computing, processing, deriving, investigating, looking up (e.g.,looking up in a table, a database or another data structure),ascertaining and the like. Also, “determining” may include resolving,selecting, choosing, establishing and the like.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array signal (FPGA) or other programmable logicdevice, discrete gate or transistor logic, discrete hardware componentsor any combination thereof designed to perform the functions describedherein. A general purpose processor may be a microprocessor, but in thealternative, the processor may be any commercially available processor,controller, microcontroller or state machine.

The operations and functions of the various logical blocks, modules, andcircuits described herein may be implemented in circuit hardware orembedded software codes that can be accessed and executed by aprocessor.

While the disclosure has been described by way of example and in termsof the preferred embodiments, it is to be understood that the disclosureis not limited to the disclosed embodiments. To the contrary, it isintended to cover various modifications and similar arrangements (aswould be apparent to those skilled in the art). Therefore, the scope ofthe appended claims should be accorded the broadest interpretation so asto encompass all such modifications and similar arrangements.

What is claimed is:
 1. A power control method, performed by acommunication device, comprising: determining a power range of atransmit power of an uplink output signal; determining a gain switchrange based on the power range transmit power, wherein the gain switchrange is defined between a first power and a second power, and whereinthe second power is larger than the first power; and when the transmitpower of the uplink signal is within the gain switch range, determininga first gain mode for amplifying the uplink signal; and when thetransmit power of the uplink signal is out of the gain switch range,determining a second gain mode for amplifying the uplink signalselectively amplifying the output signal using one of a high gain modeand a low gain mode, wherein when the communication device is in the lowgain mode and the transmit power increases above the second power,switching from the low gain mode to the high gain mode, and when thecommunication device is in the high gain mode and the transmit powerdecreases below the first power, switching from the high gain mode tothe low gain mode.
 2. The power control method of claim 1, furthercomprising: receiving a downlink an input signal from an air interface;and determining external information according to the downlink inputsignal, wherein, the determining the power range step comprises,determining the transmit power of the uplink signal output signal isdetermined according to the external information.
 3. The power controlmethod of claim 1, further comprising: configuring internal information,wherein, the determining the power range step comprises, determining thetransmit power of the uplink signal output signal is determinedaccording to the internal information.
 4. The power control method ofclaim 1, wherein, the when the transmit power of the uplink signal isout of the gain switch range step comprises: determining a first signalquality using the first gain mode; determining a second signal qualityusing the second mode; and when the second signal quality is less thanor equal to the first signal quality, amplifying the uplink signal withthe first gain mode.
 5. The power control method of claim 1, wherein,the determining the power range step comprises, applying digitalmodulation and available radio resources are applied to the uplinkoutput signal to determine the transmit power.
 6. The power controlmethod of claim 1, wherein: thea power range of the transmit powercomprises an upper power range defined by an upper limit power and anaverage power; and the step of determining the power range step gainswitch range based on the transmit power comprises, determining the gainswitch range selecting one of a plurality of predefined gain switchranges according to the upper power range.
 7. The power control methodof claim 1, further comprising: receiving a downlink an input signalfrom an air interface to determine external information; and configuringinternal information, wherein the internal information and the externalinformation correspond to first and second priorities, respectively, thedetermining the power range transmit power step comprises, determining afirst power range according to a first transmit power of the uplinkoutput signal according to the external information, and determining asecond power range according to a second transmit power of the uplinkoutput signal according to the internal information, and the step ofdetermining the gain switch range step based on the transmit powercomprises, determining a first gain switch range according to the firstpower range transmit power, determining a second gain switch rangeaccording to the second power range transmit power, and determining oneof the first and the second gain switch ranges as the gain switch rangebased on the first and second priorities.
 8. The power control method ofclaim 1, further comprising: receiving a downlink an input signal froman air interface to determine external information; and configuringinternal information, wherein, the determining the power range transmitpower step comprises, determining a first power range according to afirst transmit power of the uplink output signal according to theexternal information, and determining a second power range according toa second transmit power of the uplink output signal according to theinternal information, and the step of determining the gain switch rangestep based on the transmit power comprises, determining a first gainswitch range according to the first power range transmit power,determining a second gain switch range according to the second powerrange transmit power, and determining a corresponding gain switch rangeof a smaller one of the respective first and the second power ranges ofthe first and the second transmit powers as the gain switch range. 9.The power control method of claim 1, further comprising: receiving adownlink an input signal from an air interface to determine externalinformation; and configuring internal information, wherein, thedetermining the power range transmit power step comprises, determining afirst power range according to a first transmit power of the uplinkoutput signal according to the external information, and determining asecond power range according to a second transmit power of the uplinkoutput signal according to the internal information, the step ofdetermining the gain switch range step based on the transmit powercomprises, determining a first gain switch range according to the firstpower range transmit power, determining a second gain switch rangeaccording to the second power range transmit power, and determining acorresponding gain switch range of a larger one of the respective firstand the second power ranges of the first and the second transmit powersas the gain switch range.
 10. A communication device, comprising: acontroller control circuit, configured to determine a power range of atransmit power of an uplink output signal, and determine a gain switchrange based on the power range, when the transmit power of the uplinksignal is within the gain switch range, determine a first gain mode, andwhen the transmit power of the uplink signal is out of the gain switchrange, determine a second gain mode transmit power, wherein the gainswitch range is defined between a first power and a second power, andwherein the second power is larger than the first power; and a poweramplifier, coupled to the controller control circuit, configured toamplify the uplink signal with the first or the second output signal ina low gain mode or a high gain mode, wherein the control circuit isfurther configured to switch the power amplifier from the low gain modeto the high gain mode when the power amplifier is in the low gain modeand the transmit power increases above the second power, and to switchthe power amplifier from the high gain mode to the low gain mode whenthe power amplifier is in the high gain mode and the transmit powerdecreases below the first power.
 11. The communication device of claim10, further comprising: a receiver, coupled to the controller controlcircuit, configured to receive a downlink an input signal from an airinterface, wherein the controller control circuit is configured todetermine external information according to the downlink input signal,and determine the transmit power of the uplink output signal accordingto the external information.
 12. The communication device of claim 10,wherein the controller control circuit is adapted to configure internalinformation, and determine the transmit power of the uplink outputsignal according to the internal information.
 13. The communicationdevice of claim 10, wherein the controller is configured to determine afirst signal quality using the first gain mode, and determine a secondsignal quality using the second mode, and when the second signal qualityis less than or equal to the first signal quality, the power amplifieris configured to amplify the uplink signal with the first gain mode 14.The communication device of claim 10, wherein the controller controlcircuit is configured to apply digital modulation and available radioresources to the uplink output signal to determine the transmit power.15. The communication device of claim 10, wherein the a power range ofthe transmit power comprises an upper power range defined by an upperlimit power and an average power, and the controller control circuit isconfigured to determine select one of a plurality of predefined gainswitch ranges as the gain switch range according to the upper powerrange.
 16. The communication device of claim 10, further comprising: areceiver, coupled to the controller control circuit, configured toreceive a downlink an input signal from an air interface to determineexternal information, wherein the controller control circuit is adaptedto configure internal information, the internal information and theexternal information correspond to first and second priorities,respectively, the controller control circuit is configured to determinea first power range according to a first transmit power of the uplinkoutput signal according to the external information, and determine asecond power range according to a second transmit power of the uplinkoutput signal according to the internal information, and determine afirst gain switch range according to the first power range transmitpower, determine a second gain switch range according to the secondpower range transmit power, and determine one of the first and thesecond gain switch ranges as the gain switch range based on the firstand second priorities.
 17. The communication device of claim 10, furthercomprising: a receiver, coupled to the controller control circuit,configured to receive a downlink an input signal from an air interfaceto determine external information, wherein the controller controlcircuit is adapted to configure internal information, the internalinformation and the external information correspond to first and secondpriorities, respectively, the controller control circuit is configuredto determine a first power range according to a first transmit power ofthe uplink output signal according to the external information, anddetermine a second power range according to a second transmit power ofthe uplink output signal according to the internal information, anddetermine a first gain switch range according to the first power rangetransmit power, determine a second gain switch range according to thesecond power range transmit power, and determine a corresponding gainswitch range of a smaller one of the respective first and the secondpower ranges of the first and the second transmit powers as the gainswitch range.
 18. The communication device of claim 10, furthercomprising: a receiver, coupled to the controller control circuit,configured to receive a downlink an input signal from an air interfaceto determine external information, wherein the controller controlcircuit is adapted to configure internal information, the internalinformation and the external information correspond to first and secondpriorities, respectively; the controller control circuit is configuredto determine a first power range according to a first transmit power ofthe uplink output signal according to the external information, anddetermine a second power range according to a second transmit power ofthe uplink output signal according to the internal information, anddetermine a first gain switch range according to the first power rangetransmit power, determine a second gain switch range according to thesecond power range transmit power, and determine a corresponding gainswitch range of a larger one of the respective first and the secondpower ranges of the first and the second transmit powers as the gainswitch range.
 19. The power control method of claim 1, furthercomprising determining an initial gain mode of the communication deviceby performing the steps of: when the transmit power of the output signalof the communication device on initialization is within the gain switchrange, using a default value for the initial gain mode, wherein thedefault value is one of the high and low gain modes; when the transmitpower of the output signal of the communication device on initializationis lower than the first power, using the low gain mode; and when thetransmit power of the output signal of the communication device oninitialization is higher than the second power, using the high gainmode.
 20. The communication device of claim 10, wherein the controlcircuit is further configured to determine an initial gain mode of thecommunication device, the initial gain mode being determined as follows:when the transmit power of the output signal of the communication deviceon initialization is within the gain switch range, a default value isused for the initial gain mode, wherein the default value is one of thehigh and low gain modes; when the transmit power of the output signal ofthe communication device on initialization is lower than the firstpower, the low gain mode is used; and when the transmit power of theoutput signal of the communication device on initialization is higherthan the second power, the high gain mode is used.